Gonzaga’s Kelly Olynyk, bottom, gets tangled up with Southern University’s Javan Mitchell during the second half of their NCAA tournament game in Salt Lake City Thursday.

SALT LAKE CITY — Still don’t think Gonzaga deserved that No. 1 seed? There might be a few more doubters now.

Entering the NCAA tournament top-seeded and top-ranked for the first time in program history, the Zags nearly made another kind of history Thursday — coming only a few minutes and a rimmed-out shot or two from becoming the first 1 to lose to a 16.’

Gonzaga prevailed 64-58 over Southern University in a game that wasn’t safely in hand until the final buzzer sounded. No. 1 seeds improved to 113-0 since the field was expanded to 64 teams in 1985.

Kelly Olynyk led the Zags (32-2) with 21 points, though it was a pair of 3-pointers — one by Gary Bell Jr., the next by Kevin Pagnos — that gave Gonzaga its small cushion after Southern (23-10) tied things at 56 with 3:45 left.

Bell’s 3 made it 59-56 after Derick Beltran hit a 14-footer on the baseline to close out a 15-4 Southern run and tie the game.

Beltran hit two free throws to cut the deficit to one, but Gonzaga responded by working the ball to Pagnos, whose 3 made it a four-point game.

Yondarius Johnson and Malcom Miller both had open looks on the next possession for Southern but neither could convert.

Pagnos (16 points) made two free throws with 14.3 seconds left to seal the deal. But when Zags coach Mark Few shook hands with his counterpart, Roman Banks, at midcourt, it was hard to tell who won; Banks looked like he was doing the consoling.

Something of a fitting start to the tournament in this season filled with upsets, shifts atop The Associated Press poll and no dominant team.

Critics of Gonzaga felt the West Coast Conference champions got to No. 1 by default more than anything.

The Zags shut out that talk and said they’d take their first game as NCAA tournament front-runners the way they’d taken the previous 33.

But they ran into a team in Southern, enrollment 6,900 out of Baton Rouge, La., and champions of the Southwestern Athletic Conference, that wasn’t intimidated by the Zags, but rather spent the season trying to emulate them.

The Jaguars spent much of the game bringing back memories of Princeton’s near upset of top-seeded Georgetown in 1989, and East Tennessee State’s one-point loss to No. 1 Oklahoma that same tournament.

Playing through the death of Rick Majerus in December, Saint Louis reached another mark for its late coach. The Billikens (28-6) eclipsed the 1988-89 team’s school record of 27 victories.

Evans shot 11 of 16 and finished a point shy of his career best to propel Saint Louis past 7-foot-5 New Mexico State freshman Sim Bhullar. The Billikens held Bhullar to four points, 11 rebounds and three blocks.

Bandja Sy had 17 points and nine rebounds for the 13th-seeded Aggies (24-11), who shot just 28 percent.

Oregon 68, Oklahoma St. 55

SAN JOSE, Calif. — Damyean Dotson scored 17 points and Arsalan Kazemi added 11 points and 17 rebounds to help 12th-seeded Oregon extend a run that began in the Pac-12 tournament by beating fifth-seeded Oklahoma 68-55 in the second round of the NCAA tournament on Thursday.

Dominic Artis scored 13 points and helped frustrate Oklahoma State star freshman Marcus Smart on the defensive end to give the Ducks (27-8) their first tournament win in six years.

Oregon advanced to play fourth-seeded St Louis (27-6) on Saturday for a spot in the Midwest regional in Indianapolis next week. The Billikens beat New Mexico State 64-44.

Smart came into the game with the hype of a top NBA prospect but was held to 14 points on 5 for 13 shooting for the Cowboys (24-9).

Marquette 59, Davidson 58

LEXINGTON, Ky. — Vander Blue’s layup with one second left capped Marquette’s rally from a nine-point deficit and gave the third-seeded Golden Eagles a 59-58 victory over Davidson Thursday in the NCAA tournament.

Blue and Jamil Wilson made consecutive 3-pointers to bring Marquette within 58-57 with 11 seconds left. The Golden Eagles then caught a huge break when De’Mon Brooks’ long inbounds pass went out of bounds at midcourt with 5.5 seconds left, providing another opportunity.

Blue took full advantage after getting Wilson’s inbounds pass, driving left and finding room for the winning basket. He then sealed Marquette’s improbable win by stealing Davidson’s last-ditch inbounds pass at midcourt to set off a celebration among players and Golden Eagles fans at Rupp Arena.

Blue scored seven of Marquette’s final 11 points to finish with 16. Wilson added 14 points as the Golden Eagles (24-8) won for the fifth time in six games and advanced to face Butler in Saturday’s third-round game.

The Bulldogs beat Bucknell, 68-56.

Jake Cohen’s 20 points led Davidson (26-8), who seemed in control leading 49-40 with 6½ minutes left before Marquette rallied.

Memphis 54, St. Mary’s 52

AUBURN HILLS, Mich. — Matthew Dellavedova’s 3-pointer from the right wing sailed long as time expired, allowing sixth-seeded Memphis to hold on for a 54-52 win over 11th-seeded Saint Mary’s on Thursday.

The Tigers (31-4) led by 15 in the first half but nearly gave the game away in the final seconds. With Saint Mary’s (28-7) down five, Eividas Petrulis banked in a 3-pointer with 3.1 seconds to play. Memphis then lost the ball when Jordan Giusti deflected the inbound pass off Joe Jackson of the Tigers and out of bounds.

Dellavedova, the career leader in scoring for the Gaels, was able to get a shot off from in front of his team’s bench, but it was well long, missing everything.

Butler 68, Bucknell 56

LEXINGTON, Ky. — Andrew Smith had a double-double including a career-high 16 rebounds, Roosevelt Jones added 14 points and Butler made its free throws down the stretch to hold off upset-minded Bucknell 68-56 in the second round of the NCAA tournament on Thursday.

After trailing for most of the game, 11th-seeded Bucknell got back into it with a 19-2 second-half run. But after Joe Willman’s jumper cut Butler’s lead to 43-42 with 6:56 left, the Bison (28-6) went almost five minutes without scoring. Butler went 18-of-20 at the line in the last 4:43.

Willman scored a career-high 20 points for Bucknell, but the Bison couldn’t overcome an off day by two-time Patriot League Player of the Year Mike Muscala. Bucknell’s all-time leading scorer had nine points, only the second time this season he’d failed to reach double figures.

Butler will face the winner of Davidson-Marquette on Saturday.

Michigan State 65, Valparaiso 54

AUBURN HILLS, Mich. — Derrick Nix’s strength and skill were much too much for Valparaiso.

Nix had 23 points and a career-high 15 rebounds to help power third-seeded Michigan State past the 14th-seeded Crusaders 65-54 on Thursday in the NCAA tournament.

The Spartans went on a 26-5 run in the first half to take control, and cruised to an easy victory.

Michigan State (26-8) will play the winner of the Memphis-St. Mary’s game on Saturday when coach Tom Izzo’s Spartans will be shooting for a spot in the round of 16 for the fifth time in six years.

The Crusaders (26-8) were no match for Michigan State in their first NCAA tourney in nine years, just as they weren’t as a first-round loser in 2000 to the eventual champion Spartans.

Valpo had enough size to match up, but didn’t have enough strength.

The Crusaders didn’t seem worried about the 6-foot-9, 270-pound Nix when asked about him the day before the game.

Valpo’s 6-8, 240-pound forward Kevin Van Wijk nonchalantly said he and his teammates faced similar players in the Horizon League. If that’s true, it didn’t seem to prepare Van Wijk and his fellow post players for Nix’s brute force, relatively nimble feet and soft hands.

Nix had nine points in the first half when he made his fourth shot to put Michigan State ahead 32-12. At that point, he had as many field goals as the Crusaders’ entire team. That basket was scored after backing down Bobby Capobianco so much that the 6-10, 245-pound forward fell on his back as if he was hit by a linebacker. Nix scored 14 in the second half, falling two points shy of matching his career high.

Van Wijk, meanwhile, missed both of his shots in the first half. He fouled out without making any of his six attempts and finishing with two points — well below his 12.7-point average. Valpo’s other post player and leading scorer, Ryan Broekhoff, scored eight points — half his average — on 2 of 11 shooting.

Erik Buggs scored 14 and Matt Kenney had 10 points for the Crusaders, whose coach Bryce Drew called as many timeouts as he could to slow down the Spartans.

It didn’t work.

While Nix dominated on the inside, Michigan State guards Keith Appling and Gary Harris gave the team offensive balance by making jumpers. Appling scored 15 points — making three 3-pointers — and Harris had 10 points.

When Valpo went to a zone early in the game when the score was tied at 8, Harris made a 3-pointer to put the Spartans ahead for good. He made another 3-pointer during the game’s decisive run, making his extra work earlier in the week pay off for him and his team.

More than an hour after Monday’s practice, Harris was back in the gym. He got a collapsed ball-return machine out of a corner by himself, wheeled it under a rim and set it up to put up some high-arcing shots. He made 52 of his first 71 shots, mostly from long range, during a personal workout thanks to a sweet stroke that has served the freshman — and the Spartans — well this season.